Electron-loss-to-continuum cusp in collisions of U$^{89+}$ with N$_{2}$ and Xe

TL;DR

This study investigates the electron-loss-to-continuum cusp in highly charged uranium ion collisions with N$_2$ and Xe, revealing energy shifts and testing relativistic theoretical models with experimental data.

Contribution

It provides the first detailed experimental comparison of ELC cusp shapes for different targets and tests relativistic calculations against observed data.

Findings

Significant energy shift of the ELC cusp centroid with Xe compared to N$_2$.

Experimental data agree with relativistic continuum-distorted-wave calculations.

Results challenge and refine theoretical models of electron emission in heavy ion collisions.

Abstract

We study the electron-loss-to-continuum (ELC) cusp experimentally and theoretically by comparing the ionization of U$^{89+}$ projectiles in collisions with N$_2$ and Xe targets, at a beam energy of 75.91 MeV/u. The coincidence measurement between the singly ionized projectile and the energy of the emitted electron is used to compare the shape of the ELC cusp at weak and strong perturbations. A significant energy shift for the centroid of the electron cusp is observed for the heavy target of Xe as compared to the light target of N$_2$. Our results provide a stringent test for fully relativistic calculations of double-differential cross sections performed in the first-order approximation and in the continuum-distorted-wave approach.